Chances are if you have gone shopping for a new TV any time in the past five years you stumbled into a mire of confusing issues about specifications and connections.
Back in the good old days you could bring home your TV, plug it in, and connect a single cable, which you may run through your VCR first so that you can record TV programs.
Now TV’s, like everything else, have gone digital and instead of a single cable to connect, you have many choices. It’s hard to figure out what you really need and whether the sales clerk really has your interests in mind when he’s telling you it won’t work unless you spend this extra couple of hundred dollars on cables.
Is this like that extended warranty that the store urges you to buy, knowing that you will probably never need it?
You want a high-def TV because everybody tells you it’s the only way to go. And the clerk tells you it won’t really be high-def unless you connect one of these expensive HDMI cables. Is it true? And just what is HDMI anyway?
As television images improved the cables carrying the signal had to improve as well. Still in the analog domain, first there was S-Video, a small cable that gave you an improved video picture but didn’t carry audio and wasn’t high-def.
For years, boardroom projectors had used cables that broke the colour video signal into its five component parts: three primary colours and two timing signals for vertical and horizontal. This five-cable array was improved upon by the advent of component cables – three cables (red, green and blue) to carry the colour, with the timing signals piggybacked on to the green cable. These cables were and are sufficient to carry a high definition video picture, even though they carry analog, not digital signals.
The clerk at the store may tell you that you are much better off with the HDMI cables because, since they are all digital, there will be no loss of quality in converting back and forth between digital and analog. But it is a specious argument.
The fact is that using good quality analog component cables will give you as good a picture as you can get, with no worries of interference or degradation. And even if you stay entirely within the digital realm it’s not a straight road, as there are still going to be many conversions and scaling going on which can be as problematic as flipping between digital and analog. In reality, the only advantage of HDMI over component cables is that the audio is included with the video.
The real beneficiaries of the HDMI interface are the movie studios. HDMI stands for High Definition Media Interface and it’s all digital. In addition to sending digital bitstreams of the three basic colours and the timing it delivers three data channels and these channels allow the cable to pass content protection between devices. The uncompressed datastream from an HDMI cable can’t be recorded. That’s why the movie studios like it; it has nothing to do with performance. The point is you can’t make copies from an HDMI cable.
So maybe that’s not a big deal. There’s nothing wrong with the people who create the entertainment protecting their right to profit from it. Just don’t let them tell you it’s for your benefit. There are problems associated with HDMI cables that you won’t find with the component cables.
Before HDMI there was DVI, the Digital Video Interface. It too was entirely digital, and it too contained copy protection, but it didn’t include the audio, which still had to be sent by separate cables. Sometime between DVI and the introduction of HDMI there was the development of HDCP, or High-bandwidth Digital Content Protection.
It works like the computer security protocols that require a handshake between the transmitter and receiver to ensure that none of the data goes astray. The problem is that early devices such as DVD players that included a DVI output didn’t incorporate HDCP so if you connect them to a newer device that does the DVI connection won’t work.
Now the Motion Picture Association of America is urging equipment manufacturers to scale down the analog output so that component cables will no longer carry high-def, not because the cables are insufficient but because the new devices won’t output hi-def on the component outputs.
This would be great for the MPAA, not so great for you if you get a new cable box or Blue-Ray player and it won’t work with the component cables.
Because of the high-tech nature of HDMI cables, the ends are installed at the factory. They can’t be done on site because a discrepancy in length as small as a thousandth of an inch will cause the cable to fail. They are limited to around 15 meters in length and the longer they are the greater risk of problems.
The standard for HDMI cables, currently at version 1.4, is constantly being upgraded, but the newer cables are still compatible with the old devices so it’s not a problem. You’ll find that prices vary considerably and, in this case, costlier is not necessarily better.
Because the signals passed by the HDMI are in the form of a digital bitstream, the physical characteristics of the cable are not as important so sometimes a cheap cable will work as well as an expensive one.
The one potential problem is related to the inability of the HDMI cable to maintain a constant impedence, leaving room for digital errors that could destroy the entire transmission. For the most part, though, the quality of the transmission depends more on the quality of the circuitry in the source and display devices, something which does not apply to the same degree in the analog world.
By far the greatest problem with HDMI cables is a decidedly low-tech one. The ends of the cable, which plug into your source at one end and your display at the other, are not big enough for the weight of the cable. It’s essentially a design error.
Computer cables with big connectors like this on the end usually include a screw-down locking ability but HDMI cables don’t. Often the cable will come loose in its seated position, an aggravation at the very least. A bigger problem is that the weight of the cable can possibly damage the port on your source or display, which can be an expensive thing to fix. This problem is eliminated in the latest 1.4 version, which has a plug about half the size of the previous version.
One way to approach the problem of a heavy cable end is to install a port saver. This is an 8” extender on the end of the cable, lighter than the cable itself so that the pressure on the port is reduced.
The advent of HDMI and the HDCP protection is good because, as an anti-piracy system it works, and that means that the Hollywood studios can feel safe to release their movies on Blu-Ray discs knowing pirates can’t make copies from them.
Nowadays every high definition TV has one or more HDMI input but there were several million high-def TV’s sold before HDMI and these sets are still in people’s homes, connected by component cables.
If the industry succeeds in restricting the quality of output at component jacks (and they can do this on the disc itself) these TV’s will be useless as high-def displays (and, to add insult to injury, those early adaptors probably paid ten times what they would pay today for a better TV).
It’s a case that we have become so familiar with in the twenty-first century of technologies becoming obsolete before they wear out. Forcing us back to the store.
Bill Monahan is a “smart home” specialist who has been in the construction industry for thirty years, with the last twelve devoted exclusively to residential electronics. While he provides and installs products he sees his main mission as making homeowners comfortable with the new technologies.
